I typically use Petsc Nonlinear Solvers in 3D and my bottle neck is 
typically in the assembly with Petsc SNESSolve taking ~10% of the time
about ~50% in the jacobian, ~30% in the residual, and the
rest is distributed.






On Thu, 24 Jun 2010, Jed Brown wrote:

> On Thu, 24 Jun 2010 13:23:37 -0500 (CDT), David Fuentes <[email protected]> 
> wrote:
>> Thank you Roy,
>>
>>
>> I typically use 1-2, p=1, variables per system.
>
> In 2D or 3D?  Virtual calls compile to "mov, mov, jmp", the indirect
> call typically costs 5 or 6 cycles (because data dependence interferes
> with OoO), compared to 2 (partly hidden by OoO) for a static call.
> Evaluating a 3D basis function still costs enough that the indirect call
> should not be a very serious hit.  It probably looks nontrivial compared
> to evaluating 2D basis functions.  None of this matters if your
> quadrature involves nontrivial physics or the solver isn't very good.
>
> Jed
>

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